64 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



cylindric, with large, relatively thin, persistent scales longer than the 

 erose-dentate or nearly entire bracts; seeds small, winged. 



On the Kaibab Plateau, in the White Mountains, and on the summit 

 of Mount Graham the Engelmann spruce occurs in extensive stands 

 which afford protection to the headwaters of streams. Present con- 

 ditions are unfavorable to commercial exploitation in this State, but 

 elsewhere the wood, which is rather weak and knotty, is utilized to 

 some extent, chiefly for making boxes. Both species that occur in 

 Arizona are valuable ornamentals but thrive only in a cool moist 

 climate. They are in demand for Christmas trees. Some species of 

 spruce are very important as a source of paper pulp. 



Key to the species 



1. Young branches and petiolelike leaf bases commonly pubescent or puberulent; 

 leaves not rigid, acute or acutish at apex; cones commonly about 5 cm. 

 long, the scales more or less rounded and distinctly thinner at apex. 



1. P. ENGELMANNI. 



1. Young branches and leaf bases commonly glabrous; leaves rigid, spinescent- 

 acuminate at apex; cones commonly about 8 cm. long, the scales truncate 

 and not distinctly thinner at apex 2. P. pungens. 



1. Picea engelmanni Parry in Engelm., Acad. Sci. St. Louis Trans. 2: 



212. 1863. 



Kaibab Plateau, San Francisco Peaks, White Mountains, Pinaleno 

 Mountains, and Chiricah.ua Mountains (Coconino, Apache, Graham, 

 and Cochise Counties), 8,000 to 12,000 feet, often in dense stands. 

 British Columbia through the Rocky Mountains to New Mexico and 

 Arizona, and through the Pacific Coast States to northern California. 



Engelmann spruce. Attains a height of 30 m. (100 feet) and a 

 trunk diameter of 90 cm. (3 feet), but is perhaps rarely so large in 

 Arizona. Trunk straight and tapering, crown narrow-pyramidal, 

 pointed and short in dense stands, but in widely spaced trees much 

 longer, with drooping branches often extending nearly to the ground. 

 Bark of older trunks russet to dark purplish brown or gray brown, 

 thin, hard, splitting into plates. This species affords some sawed 

 lumber, especially on Mount Graham, where growth conditions are 

 good. 



2. Picea pungens Engelm., Gard. Chron., ser. 2, 11: 334. 1879. 



Picea parry ana (Andre) Sarg., Silva North Amer. 12: 47. 

 1898. 



Kaibab Plateau (Coconino County), Lukachukai and White 

 Mountains (Apache County), 7,000 to 11,000 feet, sometimes in dense 

 stands. Wyoming to New Mexico and Arizona. 



Blue spruce. This species is less widely distributed in Arizona than 

 Engelmann spruce, which it resembles in habit and appearance, 

 although usually smaller, with foliage of young trees more pronouncedly 

 glaucous and bark rougher and duller colored. According to Marco 8 

 the resin canals extend into the upper half of the leaf in P. pungens, 

 whereas in P. engelmanni they terminate in the basal half. 



3. PSEUDOTSUGA. Douglas-fir 



Tree; leaves evergreen, narrowly linear, obtuse, short-petioled, com- 

 pressed but strongly ribbed and channeled, not deciduous in drying, 



s Marco, H. F. needle structure as an aid in distinguishing Colorado blue spruce from engel- 

 mann SPRUCE. Bot. Gaz. 92: 446-449. 1931. 



